AUSTIN — Zebra mussels have been positively identified for the first time in Lake Travis in the Colorado River Basin in Central Texas, just weeks after biologists confirmed the aquatic invasive species had also spread to the Guadalupe River Basin.
Texas Parks and Wildlife Department (TPWD) and Lower Colorado River Authority (LCRA) biologists confirmed the presence of zebra mussels in Lake Travis June 22 after an observant staff member at a local marina reported the sighting of a single zebra mussel attached to the outboard motor of a moored boat on the lake.
On-site, biologists found the mussels attached to other nearby boats and on submerged marina infrastructure. Additionally, they found several size classes of adult and juvenile mussels at two different sites in the lake, indicating the lake is infested with an established, reproducing population.
“This is pretty disheartening for us and our many partners, including marinas, who work to prevent this invasive species from spreading – it’s two new river basins with infestations this year,” said Monica McGarrity, TPWD Aquatic Invasive Species team lead. “But we are very grateful to the marina staff for reporting the sighting, our partners at Texas Invasives for relaying the report to us, and the LCRA for participating in a rapid response to investigate the report.”
Brian Van Zee, Inland Fisheries regional director, said the next step after discovering a new infestation is to educate the public and local marinas to help prevent the zebra mussels from spreading further to nearby lakes.
“Public awareness goes a long way in helping with the effort to prevent zebra mussels from spreading,” Van Zee said. “This is a battle we cannot give up on – the cost of these infestations is large and affects so many people. We have to keep up the fight and try to inform the public as much as possible about how they can protect their lakes from invasive species.”
The rapidly reproducing zebra mussels, originally from Eurasia, can have serious economic, environmental and recreational impacts on Texas reservoirs and rivers. Zebra mussels can cover shoreline rocks and litter beaches with treacherously sharp shells, clog public-water intakes, and damage boats and motors left in infested waters.
Lake Travis is a 19,297-acre LCRA-managed reservoir on the lower Colorado River located 20 miles northwest of Austin. McGarrity said while there is an inevitable risk of zebra mussel larvae dispersing downstream to Lake Austin and Lady Bird Lake, the more immediate risk is that zebra mussels could hitch a ride to these locations on recreational equipment traveling from Lake Travis or other infested lakes.
“Downstream dispersal depends on the number of larvae going downstream, the conditions they experience and the timing,” McGarrity said. “But a boat can take a ready-made colony to another lake at any time – so preventing the spread within these newly infested basins is still really important. The longer we can stave off new infestations the longer we can prevent potential recreational impacts or costly impacts to infrastructure.”
In Texas, it is unlawful to possess or transport zebra mussels, dead or alive. Boaters are required to drain all water from their boat and onboard receptacles before leaving or approaching a body of fresh water in order to prevent the transfer of zebra mussels. The requirement to drain applies to all types and sizes of boats whether powered or not: personal watercraft, sailboats, kayaks/canoes or any other vessel used on public waters.
“Cleaning, draining and drying really doesn’t take much time – it’s a few simple steps that boaters can take to prevent these infestations,” McGarrity said. “There are more than 1,500 boat ramps in Texas and we can’t be everywhere, so we have to rely on boaters, marinas and concerned citizens to help in this fight.”
McGarrity said the discovery and reporting of both new infestations by marina staff this year reinforces the important role marinas play as gate keepers that can help prevent boats with attached zebra mussels from entering their lakes.
“When we have boats coming into these marinas it’s essential the staff learn about the history of the boat and ask where it is coming from, if it has been on a lake that is infested with zebra mussels, or if it has been in another state that has quagga mussels, which are literally knocking on our door,” McGarrity said. “We want marinas to inspect or work with TPWD to have boats inspected so we can prevent new infestations. We ask that they contact us whenever they have an incoming boat that’s of concern so that we can help evaluate the risks or assist with the inspection.”
Since zebra mussels were first found in Texas in 2009, 11 lakes in five river basins have been infested, meaning they have an established, reproducing population – Belton, Bridgeport, Canyon, Dean Gilbert (a 45-acre Community Fishing Lake in Sherman), Eagle Mountain, Lewisville, Randell, Ray Roberts, Stillhouse Hollow, Texoma and now Travis.
More information about zebra mussels can be found online at tpwd.texas.gov/ZebraMussels.
Marinas should contact TPWD at 512-389-4848 for assistance if zebra mussels are found on incoming boats—or for coordination when boats are leaving marinas on infested lakes.